US 5,166,606 A · High efficiency cryogenic test station

Abstract

ATE is mounted directly to a support surrounding and removably receiving probe cards of differing thickness. An electrically heated chuck having a variable heat transfer coefficient heat exchanging face confronting a liquid nitrogen supplied plenum exhibits a temperature that varies with electrical heater load, rate of liquid nitrogen supply, and heat transfer coefficient of the heat exchanging face. The rate of liquid nitrogen supply is varied as a function of whether or not the electrical heater load falls outside predetermined upper and lower bounds to establish and maintain set point temperature over a range of set point temperatures including liquid nitrogen temperature and ambient temperature. The chuck is mounted for X,Y movement on load-balanced air/vacuum bearing, and is mounted for Z movement to accommodate different thickness probe cards. A load-lock having a pivoting cassette receiving tray that pivots with a pivoting transfer arm is mounted for Z movement with the chuck. A vacuum pump selectively lowers the temperature at which the supplied liquid nitrogen boils. A positive pressure of N.sub.2 gas is maintained to prevent moisture condensation in the load-lock and on the operative surfaces of the chuck.

Claims13

Dependent claims

For use in a cryogenic test station receiving wafers having a pluality of integrated circuit devices to be tested and testing the same at any setpoint temperature over a range of setpoint temperatures and having a wafer-receiving chuck having a temperature that is cooled by a flow of a heat transfer liquid at a rate of flow and that is heated by electrical resistance heaters generating heat at a corresponding electrical power, apparatus operative to minimize both heat transfer liquid and electrical power usage in establishing and maintaining testing at any setpoint temperature, comprising:

heater controller means for varying the amount of power dissipated by the electrical resistance heaters to cause chuck tempeature to stabilize at and around any selected setpoint temperature;
and
heat transfer liquid flow controller means coupled to said heater controller means and operative in correspondence to the level of power dissipated by the electrical resistance heaters for increasing the rate of flow whenever, the power falls outside a preselected upper bound and for decreasing the rate of flow whenever the power falls outside a preselected lower bound.

Dependencies are inferred from the claim text.

High efficiency cryogenic test station

Life of this patent

High efficiency cryogenic test station

Life of this patent

Abstract

Claims13